1. V. I. Arnol'd, Ordinary Differential Equations [in Russian], Nauka, Moscow (1973).
2. I. M. Gelfand and G. E. Shilov, Generalized Functions ? Properties and Operations, Academic Press (1969).
3. V. P. Maslov, Operator Methods [in Russian], Nauka, Moscow (1973).
4. L. I. Sedov, Mechanics of Continuous Media [in Russian], Vols. I, II, Nauka, Moscow (1973).